The study of the chemistry of the structural proteins in the vitreous of humans, cows and rabbits will be continued. Particular attention will be given to the types of collagen present in these extracellular matrices, to the factors which determine the particular fibrous form of the vitreous collagen and the relationship of collagen to the other structural glycoproteins. Vitrectomy experiments will also be performed in rabbits to determine the extent to which vitreous structure is regenerated. This animal system will also be used to study intravitreal membrane formation and the nature of the inflammatory response following the intravitreal implantation of hyaluronic acid. BIBLIOGRAPHIC REFERENCES: Degenerative Changes in Vitreous Structure Following Intravitreal Injection of Blood. Swann, D. A. and Constable, I. J. Abstract, Assoc. Res. Vision Ophthalmol., April 1975. Formation of a Stable Complex Between Protein-Polysaccharide and Hyauloronic Acid. Swann, D. A., Powell, S., Broadhurst, J. B. and Sordillo, M. Abstract, Biophysics Society, February 1976.